module Bundler::SharedHelpers

def set_env(key, value)
  raise ArgumentError, "new key #{key}" unless EnvironmentPreserver::BUNDLER_KEYS.include?(key)
  orig_key = "#{EnvironmentPreserver::BUNDLER_PREFIX}#{key}"
  orig = ENV[key]
  orig ||= EnvironmentPreserver::INTENTIONALLY_NIL
  ENV[orig_key] ||= orig
  ENV[key] = value
end